1. Field of the Invention
The present invention relates to a device and a method for making connection between two electronic components, and more specifically to a connection device that enables easy connection to and removal from a board of an electronic component such as an LSI device, and to an associated method of connection.
2. Description of the Related Art
In recent years, dramatic advances have been made in the fields of computers and communication equipment, these advances made possible by great improvement in the performance of devices such as LSI devices and other various electronic components used in such equipment. Advances in the performance of LSI devices have played a particularly important role. The mother boards of computers, for example, contain a large number of LSI devices. An LSI chip is usually housed in a package of ceramic or the like, with connection made thereto using the wiring bonding method, the ceramic package being mounted onto a printed circuit board. However, because the package is extremely large compared to the LSI chip, it requires a large amount of space to mount on the board. This mounting method is not only disadvantageous from the standpoint of achieving compact electronic apparatus, but also results in a lengthening of circuit lengths, this preventing the achievement of efficient signal processing. Additionally, in a microprocessor that operates at a high speed, because of the large number of connection points that are required, it is not possible to meet this requirement using the wire bonding method. The flip-chip bonding method was developed to solve these problems of reducing the mounting surface area, establishing a large number of connection points, and reducing the connection lengths to shorten the signal delay.
The flip-chip bonding method is a method whereby solder bumps are formed by either plating or deposition on an LSI chip or on the connection part of the board, the LSI chip and board being connected by fusing the joint formed thereby. Once the LSI chip is mounted by this method, however, there is problem that it is extremely difficult to remove. If heat is applied, the solder can be melted, enabling removal of the LSI chip. However, part of the solder remains on the board, so that when a good LSI or an upgraded LSI chip is mounted on the board, deterioration of the old solder tends to cause a bad electrical connection. When a solder that include lead is used, alpha radiation from radioactive elements such as uranium and lithium that are included in minute amounts in the lead can cause faulty operation of a semiconductor element. In the case of using solder bumps, because of a CFC solvent used to remove a reducing agent such as flux that is used when making the connection, there is the possibility of exerting an deleterious effect on the global environment.
The previously used flip-chip method will be described with reference to FIG. 6. As a method of connecting an LSI chip to a board, a eutectic solder bump made of tin and lead formed on the LSI chip is caused to come into contact with the board, a flux which is a reducing agent is applied, and a fusion bond is made at a temperature of approximately 200.degree. C. (FIG. 6(a)). Then, a CFC solvent is used to remove this flux. The use of the above-noted CFC solvent is not desirable from the standpoint of protecting the global environment. Additionally, within the solder bumps, which contain lead, there is a minute amount of radioactive elements, which cause the problem of faulty operation of semiconductor elements (FIG. 6(b)). Additionally, when the joint is melted so as to remove the LSI chip, there is the problem that solder remaining on the board results in faulty connections. (FIG. 6(c)).
As described above, the prior art flip-chip method had a large number of problems.
Accordingly, it is an object of the present invention to improve on the above-noted drawbacks of the prior art, by providing a novel connection device for facilitating the connection of an electronic component such as an LSI chip to a board and removal of an electronic component from a board, enabling repeated connection thereto and removal therefrom, while providing a stable electrical contact. It is a further object of the present invention to provide a method for making the above-noted connection.